The subsea hydraulic connectors have the function of making a rigid connection between two equipment and performing the resulting sealing among them. The connector locking is performed by driving a hydraulic piston that, through the forces transmission mechanism, generates a pre-load of the connector design needed for suitable functioning.
Currently there are two basic concepts of connectors. The first concept of connector uses a parallel locking system where an interference through an assembly adjustment system is generated. This interference produces the pre-load defined in the connector design3 for a suitable functioning. This concept is applied in the connectors disclosed in the documents of the state of the art CA1224410, US2003/0151254 and US2005/0001427. The second concept of connector currently used has a friction self-locking system for performing the locking and the resulting rigid connection between two equipment. This connector type requires less components and it is much more dependent on the friction between the surfaces for applying the connector design pre-load. The state of the art documents U.S. Pat. Nos. 4,516,795, 6,070,669, 7,614,453 and 8,474,537 disclose this type of hydraulic connector.
As well known by the people skilled in the art, the wellhead connectors are designed for connecting a BOP (Blow Out Preventer) to the wellhead, directly or, indirectly via flow-line.
Typically, such connectors include an annular main body that is aligned and connected axially to the subsea wellhead. For conceiving the connection, the connector is commonly provided with a cam ring, moving radially due to a hydraulic actuator, normally a hydraulically-driven piston, forcing the cam ring and, consequently, the teething devices, for locking or unlocking purposes.
A configuration used for connecting in wellheads consisted of a clamp, generally in “C” shape, with single contact surface. Later, connections were designed with H4 profiles that are characterized for better distributing the stress compared to those used with single surface.
Between the examples of the state of the art, we may mention specifically the document U.S. Pat. No. 4,496,172 disclosing a connector comprising jaws driven by a cam ring moving in parallel with the locking ring, being linked to pistons rods in cylinders, by which an annular plate. The pistons driving are remotely and preferably performed by hydraulic fluid lines.
The document GB2480571 also illustrates a connector with multi-tooth profile scaling the load by the profile imposing better reliability in the connection and lower wear of the connector. The document U.S. Pat. No. 3,096,999 illustrates a connector with single contact surface profile.
Other examples of connectors may differ in size, shape, number of tooth, types of hydraulic actuators, locking systems etc.
The parallel locking connectors have, among others, a technical important inconvenient that is the extreme dependence of an increased number of components that allow the pressure adjustment needed for assembling the equipment, leading also to an important inconvenient of manufacturing and assembly costs. On the other hand, the friction self-locking connectors have extreme dependence between the pre-load and the friction coefficient between the surfaces of the several connector components. In addition, the friction self-locking connector shows a big sensitivity to manufacturing tolerances, making the connection susceptible to accidental unlocking, mainly in the presence of vibration, what binds the connector to include a security system aiming to avoid the said accidental unlocking for achieving higher reliability. This requirement of additional components and also for this type of connector generates a big technical inconvenient, which additionally causes a significant increase of the manufacturing, assembly costs and, consequently, the operation cost.
Therefore, it is the main object of the present invention provide a hydraulic connector, notedly for applying in wellhead in oil production and extraction operations, particularly in the seabed, solving advantageously the technical inconvenient and economic disadvantages indicated above.